Electronic devices, in particular integrated electronic devices, provide complex functionality for all kinds of applications. There is a general need to ensure that the electronic device can operate properly in order to avoid malfunctions or failure. There are many different control and monitoring tasks that may be implemented for this purpose. One of the most important issues is to ensure that the power supply voltage level of a power supply for supplying the electronic device is within acceptable limits for proper operation of the electronic device. Monitoring circuits such as power on reset (POR) circuitry or other solutions may be employed. Comparators may be coupled to the power supply voltage level in order to determine whether or not the power supply voltage level remains within a target window.
The voltage difference between two p-n junctions (e.g. diodes) operated at different current densities may be used to generate a proportional to absolute temperature (PTAT) current in a resistor. A bandgap reference voltage (Vbg) is a voltage reference based on the bandgap energy property, typically using two different sized bipolar junction transistors (BJT). A high precision bandgap voltage reference is a temperature independent voltage reference circuit widely used in integrated circuits, usually with an output voltage around 1.25V.
The bandgap is the energy difference between the top of the valence band and the bottom of the conduction band in insulators and semiconductors. There is virtually no bandgap in most metals, but a very large one in an insulator or dielectric. In a semiconductor, the bandgap is small. Technically, the bandgap is the energy it takes to move electrons from the valence band to the conduction band.
A BJT is a type of transistor that relies on the contact of two types of semiconductor for its operation. BJTs may be used as amplifiers, switches, or in oscillators, for example. Charge flow in a BJT is due to bidirectional diffusion of charge carriers across a junction between two regions of different charge concentrations. The regions of a BJT are typically called emitter, collector, and base
Other features of the present embodiments will be apparent from the accompanying drawings and from the detailed description that follows.